1. Any positive number has two square roots and is reciprocal. If the arithmetic square root of a positive number is √a, then the other square root of a is √ a,; The root sign in its simplest form cannot have a denominator.

The square root of zero is zero.

3. There are two square roots of negative numbers, which are yoked by * * * *.

4. Rationalization root: If the product of two algebras with roots no longer contains roots, then these two algebras are mutual rationalization roots, also known as mutual rationalization factors.